I mistakenly entered an incorrectly named Aggregate server while attempting to upload a form using online Build. (MS Edge)
This seems to create a perpetual uploading attempt as there is no cancellation button once started. The only answer is to close down the broswer altogether so as to clear the cache.
Admittedly I didn't wait for more than a few minutes so there could be an eventual limit to the attempted connection.
Does it time out?